The correct answer to this open question is the following.
Although the question does not provide options, we can say that the religion of Persia is called Zoroastrianism.
In ancient Persia times, it was Cyrus the Great the one who founded the empire approximately in 550 BC. The capital city of the Empire was Persepolis, modern-day Iran. The official religion in Persia was Zoroastrianism and the main religious teacher was prophet Zoroaster. One of the main characteristics of this religion was that prophet Zoroaster taught that followers should believe in the existence of one mighty god.